<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>Title</title>
</head>
<body>
<div>
    <!--isLogin初始值是false 但是需要false时让元素显示,所以取反!-->
    <div v-if="!isLogin">
        <!--javascript:void(0) 禁止超链接的跳转功能-->
        <a href="javascript:void(0)">注册</a>
        <a href="javascript:void(0)" @click="isLogin=true">登录</a>
    </div>

    <div v-else>
        <input type="text" placeholder="名字" v-model="newName" >
        <a href="javascript:void(0)" @click="arr.push(newName)">添加</a>
        <a href="javascript:void(0)" @click="isLogin=false">登出</a>
    </div>
    <ul>
        <li v-for="name in arr">{{name}}</li>
    </ul>
</div>

<script src="https://lf3-cdn-tos.bytecdntp.com/cdn/expire-1-M/vue/2.6.14/vue.min.js"></script>
<script>
    let v = new Vue({
        el:"body>div",
        data:{
            isLogin: false,
            arr:["刘备","关羽"],
            newName:""
        }
    })


</script>
</body>
</html>